Long bones are found in the upper and lower extremities and provide the body with support, mobility and strength. They also produce red and yellow bone marrow, which is essential to the production of blood cells.
Long bones are designed to provide maximum efficiency for muscle functions such as lifting and rapid movement by serving as levers in the limbs. The bones typically consist of a long shaft called the diaphysis, and two wider extremities on the ends called epiphyses. The bone contains a central medullary cavity that serves as the center for bone marrow production. While the name suggests a larger size of bone, bones such as the metacarpals in the fingers are classified as long bones.